Modern trampolines were initially developed as training tools for gymnastic tumbler athletes in the 1930s, since then expanding to be involved in a wide variety of competitive and recreational activities. Competitors have adapted sports to play on trampolines and have even established the sport of trampolining in the Olympics. Trampolines have also become ubiquitous in training astronauts, acrobats, divers, and skiers. Many people also use trampolines for play and casual exercise, with recreational trampolines being a popular fixture outside in yards and gardens.
Modern recreational trampolines generally consist of a frame, a bounce mat, a plurality of springs, and a frame pad, and are most often circular, rectangular, or octagonal in shape. They are often installed above ground level, wherein the bottom of the trampoline frame simply rests on the ground surface so that the bounce mat is located several feet in the air. To prevent the wind from blowing the trampoline away the frame is typically secured to the ground in some fashion.
Sometimes they are installed below ground level by inserting the trampoline frame into a pit or trench. In-ground, or sunken, trampolines have benefits over above ground trampolines. As a majority of an in-ground, or sunken, trampoline may hidden below ground, and you may be able to obscure from view the rest, they are less of a visual and spacial imposition. They are easier to use, especially for children, in that they obviate the need for ladders, jumping, climbing, or having to be lifted unto the bounce mat, in contrast to an above-ground trampoline. They are safer, in that they reduce the falling distance to the ground and minimize the possibilities of hitting the metal frame of the trampoline. They are easier to keep free from wear and to secure against theft and strong wind.
In-ground trampolines are basically standard above-ground trampolines only slightly adapted for in-ground installation. The adapting may be a frame with a lower height by the addition of one or more separately attachable retaining walls to the frame of the trampoline. The retaining walls are to keep the surrounding earth from getting underneath the trampoline as the bounce mat needs to be above the ground below it to operate. Other than the addition of the retaining walls, in-ground trampolines do not vary in construction or assembly, and are not specifically adapted to be installed below ground.
The retaining walls utilized for current in-ground trampolines are designed as separate add on components to a standard trampoline. This adds to the cost and the number of components required. Furthermore, retaining walls designed to be attached to a frame may not provide adequate structural integrity in the long run. Moreover, trampolines installed in pits in the ground may be susceptible to issues associated with standing or running water within the pit including rusting of the frame, soil erosion and/or becoming a breeding ground for mosquito's or the like.
What is needed is an in-ground trampoline that retains its advantages over above-ground trampolines that is specifically designed and configured to be installed below ground level to provide adequate support for the bounce mat, structural integrity for the pit walls and drainage of the pit. The specially designed in-ground trampoline is optimized for long-term use and enjoyment over current in-ground trampolines.